How do I deauthorize ADE from my old ID?

Hi, I recently downloaded ADE after not using if for sometime. I have discovered that I cannot transfer books I have downloaded from Libby to ADE because the ADE still has my old Adobe ID and password. I updated my Adobe ID and password last year. Howeve it did not update my ADE account. To deauthorize the ADE account I need my old password which I no longer remember. I have tried "Navigate to /Users//Library/Application Support/Adobe/Digital Editions and drag the activation.dat file to the trash." When I do this their is no Digital Editions in my Application Support/Adobe. How do I deauthorize my ADE account from my old email address and old password?